Superconductivity and Antiferromagnetism in NdNiO$_2$ and CaCuO$_2$: A Cluster DMFT Study

Abstract

We perform a comparative 2 × 2 real space cluster DMFT study on minimal models for NdNiO2 and CaCuO2 obtained from downfolding DFT states, using a Nambu formalism that allows for both superconducting and antiferromagnetic order. We produce a phase diagram in temperature and doping. We find that for the nickelate, like the cuprate, the stoichiometric compound is antiferromagnetic. We find superconductivity in a doping range bounded, with a small coexistence region, by the onset of antiferromagnetism at low doping and with transition temperature becoming immeasurably small at high doping. Superconductivity emerges at around the same hole doping for both compounds, but requires a larger deviation from half filling for the nickelate. Both antiferromagnetic and superconducting order lead to a partial gapping of the d x 2 −y 2 Fermi surface sheet. Our similar results for the cuprate and nickelate suggest that nickelate superconductivity is cupratelike. We compare our results to the experimental phase diagram.

Superconducting Instabilities in Strongly-Correlated Infinite-Layer Nickelates

“…3(b). This SC state is indeed similar to cuprates with small deviations from the 3D nature of the Fermi surface and agrees with previous theoretical studies of spin-fluctuation-like approaches to pairing in the infinite-layer nickelates [21,[26][27][28][29]32]. However, increasing effects of correlations in the pairing and thereby proportionally reducing the respective QP weight √ Z for orbital to α( Z sb − 1) + 1 where α ∈ [0...1], the d z 2 orbital maintains significant coherence at low energies because it is not close to a Mott-critical regime.…”

“…The main debate is between moderately-to-strongly correlated Ni-d x 2 −y 2 -driven physics, and multi-orbital Ni(3d) mechanisms [24,25]. In the former case, SC nickelates are described as cuprate-like with a dominant d x 2 −y 2 -wave SC pairing [21,[26][27][28][29][30][31][32]. If additional SD-driven Kondo correlations are taken into account, other intriguing d-wave and also s-wave pairing solutions may become stabilized [33].…”

Characterizing the superconducting instability in a two-orbital $d$-$s$ model: insights to infinite-layer nickelate superconductors

“…Pairing symmetry: Our present work follows the established framework of d-wave symmetries based pairing mechanism 30,31,55,[66][67][68][69] . However, the most recent London penetration measurement strongly challenges this scenario by revealing the predominantly nodeless pairing 70 .…”

Charge order from the local Coulomb repulsion in undoped infinite-layer nickelates

“…These are all different from cuprates and have stimulated heated debate concerning the nature of the nickelate parent state, from which superconductivity is born upon hole doping. Although several theoretical scenarios [16][17][18][19][20] have been proposed to emphasize the key role of Mott physics, a growing consensus is that multi-band physics is indispensable in nickelates [21][22][23][24][25][26][27][28][29][30][31][32]. What has not been sufficiently explored is whether this multi-band feature may lead to some unique experimental consequences in the infinite-layer nickelates.…”